Ratiometric fluorescence and colorimetric sensing of anion utilizing simple Schiff base derivatives

Two ratiometric fluorescence and colorimetric anion sensors were designed and synthesized according to simple Schiff base reaction. Two compounds 1 and 2 were characterized by ESI-MS, elemental analyses and H-1 NMR. The sensors could give fast and visible color changes from yellow to red upon presence of the strong basic anions such as acetate ion. In particular, two compounds exhibited marked blue shifts (about 136 nm) in their emission spectra, when interacting with anions. Accordingly, the compounds 1 and 2 could act as real-time ratiometric fluorescence and colorimetric sensors for anions.